docs: def _cleanup_temporary_files(self):
          # type: (Downloader) -> None
          """Cleanup temporary files in case of an exception or interrupt.
          This function is not thread-safe.
          :param Downloader self: this
          """
          # iterate through dd map and cleanup files
          for key in self._dd_map:
              dd = self._dd_map[key]
              try:
                  dd.cleanup_all_temporary_files()
              except Exception as e:
                  logger.exception(e)